Fire protection system

ABSTRACT

A method of fire protection in which extinguishant is delivered to a plurality of discharge heads located in the space to be protected from fire. The number of heads that are opened to deliver extinguishant in response to a fire situation is limited to those located in the immediate vicinity of the fire. In this manner the opened heads are not robbed of valuable extinguishant, and water damage to materials located in areas remote to the fire is minimized. A discharge head utilized in the above method.

United States Patent Livingston 1 Mar. 27, 1973 1 FIRE PROTECTION SYSTEM [56] References Cited [75] Inventor: William L. Livingston, Sharon, UNITED STATES PATENTS Mass. 1,953,671 4/1934 Conran 169/5 2,389,332 11/1945 T den ..l69/37 [73] Assignee: liactory Mutual Research Corpora- 3,227,219 H1966 Bayer 31 ""1695 X Boston, Mass- 3,309,028 3/1967 Zieg et a1 ..l69/16 x [22] Filed: Jan. 10, 1972 Appl. No.: 216,845

Related U.S. Application Data U.S. Cl ..169/1 A, 169/16, 169/37 Int. Cl ..A62c 37/08 Field of Search ..169/l R, 1 A, 1 B, 2 R, 5,

Primary Examiner-M. Henson Wood, Jr. Assistant ExaminerMichael Mar Attorney-Warren B. Kice et a1.

[ ABSTRACT A method of fire protection in which extinguishant is delivered to a plurality of discharge heads located in the space to be protected from fire. The number of heads that are opened to deliver extinguishant in responseto a fire situation is limited to those located in the immediate vicinity of the fire. In this manner the opened heads are not robbed of valuable extinguishant, and water damage to materials located in areas remote to the fire is minimized. A discharge head utilized in the above method.

19 Claims, 12 Drawing Figures SHEET 10F 6 IIIIIIIIIL PATENTEUHARZY 1973 PATENTEUmzvma 2,5535

SHEET 2 OF 6 FIRE PROTECTION SYSTEM CROSS REFERENCES TO RELATED APPLICATIONS This application is a divisional of Ser. No. 72,333, filed Sept. 15, 1970, now US. Pat. No. 3,653,444, entitled Fire Protection System, which is turn is a continuation-in-part of copending application Ser. No. 864,612

filed Oct. 8, 1969, now US. Pat. No. 3,645,338, entil tled Improved Fixed Fire Extinguishing System and copending application Ser. No. 885,501 filed Dec. 16, 1969, now abandoned, entitled Adaptive Sprinkler Head.

BACKGROUND OF THE INVENTION Automatic extinguishant discharge systems for protecting industrial and commercial properties are almost exclusively sprinkler systems and employ thermally releasable sprinkler heads located near the top of the space being protected. The sprinkler heads are supplied with a suitable extinguishant, such as water, by a pipe network of mains, risers, cross mains and branches. Most sprinkler heads used in automatic sprinkler systems have a one-half inch discharge opening or throat normally closed by a plug retained by a thermal fuse and collapsible linkage bridging an external loop or yoke. Upon actuation of the head by collapse of the linkage, the extinguishant stream issuing from the throat impinges against a serrated deflector disc to form a hemispherical pattern of droplets simulatin g the characteristics of rain.

Because of the high degree of head standardization, design parameters for automatic sprinkler systems have, in the past, been limited to a selection of head release temperatures, head spacing and system supply capacity, including pipe sizes and the like. In the selection of a head release temperature it has been conventional practice to select sprinklers with higher temperature ratings than those which would respond quickly to the existence of a fire in the protected space. Although such a delayed response is sometimes undesirable, the disadvantages are outweighed by such advantages as avoidance of accidental release and potential loss by water damage, and the avoidance of heads located remotely from the actual fire being actuated'by the effects of convection and the circulation of hot combustion products throughout the protected space. This latter factor is believed to be one of the principal causes for failure of automatic sprinkler systems, particularly in the case of intense high challenge fires where all available extinguishant is needed on and near the burning fuel surfaces to bring the fire under control.

The selections of head spacing and water supply capacity for water sprinkler systems are predicated largely on the required water density needed to extinguish the most intense fire anticipated and on economic considerations. For example, since the maximum amount of extinguishant capable of being delivered by one head is relatively fixed by the size of its discharge orifice (usually one-half inch in diameter), increased densities have been achieved in the past by overlapping the floor areas to which extinguishant is directed by each of the heads. In other words, where increased densities are called for, the number of heads employed in the system is increased and the spacing between heads reduced to achieve overlapping coverage. The capacity of the water supply required to supply such heads has in the past involved the application of conventional principles of fluid flow, taking into account the flow requirements of all of the sprinkler heads when operating under the conditions presented by the most destructive fire which is anticipated.

Although automatic sprinkler systems of the type described have been an effective means for the protec- 0 tion of property against loss or damage by fire, the

trend during recent years to higher storage enclosures coupled with the increased use of plastics has presented new challenges for such systems. For example, recent extensive studies with actual and synthetically produced fire plumes or columns have shown that in enclosed spaces of 20 feet and higher, the updraft or chimney effect caused by convection alone is sufficient to prevent the free falling water droplets produced by conventional sprinkler heads from penetrating the rising fire plume and reaching the burning fuel surfaces. Because of this phenomenon, such sprinkler systems merely operate to wet down or inhibit the spread of a high challenge fire within the space and thus provide what is referred to as exposures protection. However, the temperatures reached in a high challenge fire are sufficient to effect a self-drying of the fuel supplying the fire. Moreover, where the fuel is plastic or plastic wrapped, it is not capable of being pre-wet by the sprinkler heads around the fire plume and hence burning proceeds substantially uninhibited. V

Another factor to be accounted for occurs where the heat of a localized high challenge fire establishing a fire column or plume in excess of 20 feet in height flares out beneath the ceiling of the protected space and actuates numerous sprinkler heads located at such a distance from the fire that they are ineffective to deliver water or other extinguishant to the fuel surfaces. This contributes not only to redundant and flooding use of the water, but more significantly, robs water from the heads over the fire where it is needed to extinguish the fire.

It will be apparent, therefore, that conventional automatic sprinkler systems, though adequate for the protection of buildings and other spaces with relatively low ceilings, are less effective in high challenge fire situations where there is adequate ceiling height for a strong intense fire plume or column to develop.

SUMMARY OF THE INVENTION In accordance with the present invention the basic approach to fighting a fire with an automatic extinguishant discharge system is changed drastically. The system is designed deliberately to limit the number of extinguishant discharge heads which will be activated by a fire. The heads are spaced apart greater distances and have large outlet orifices to enable greater quantities of water or other extinguishant to be delivered from each head at lower flow rates. Preferably, the heads are in the form of wide angle spray nozzles having 1 inch to 1% inch outlet orifices which develop a downwardly directed spray having large size droplets as compared to the droplets produced by the conventional one half inch sprinkler heads.

With this arrangement, the first head actuated by the fire has a much better possibility of extinguishing the fire because of the increased ability of the larger droplets to penetrate the fire plume of a high challenge fire. If the heat of the fire spreads, additional heads are actuated to help the first head fight the fire and to wet down areas surrounding the fire to provide exposure protection to inhibit the spread of the fire. However, the additional heads which are allowed to be actuated is limited to a small number to avoid the prior art problems created by too many heads being actuated; namely, interfering with the fire fighting capabilities of those heads positioned immediately above the fire and over the area immediately surrounding the fire, and causing unnecessary water damage by allowing an excessive number of heads to be actuated at points remote from the fire.

Extensive fire tests have established that the method of the present invention employing more widely spaced, larger nozzle heads fights high challenge fires far more effectively. Larger quantities of water or other extinguishant are delivered to the fire in a manner to penetrate the fire plume and fight the fire itself in a more effective manner, and also provide an ample, but not excessive, amount of exposure protection.

Not only does the method of the present invention improve the fire fighting performance of automatic extinguishant discharge systems, it also results in significant cost savings. The cost of automatic extinguishant discharge systems can be broken down into inside the building costs and outside the building costs. The latter includes the buried mains for delivering water to the building from a municipal water supply, and any water tanks and pumping equipment which may be needed to augment the municipal water supply. These tanks are large gravity feed tanks, or suction tanks having the necessary pumping equipment for pumping the water from the tank to the heads. The size and cost of these tanks increase in rural areas which do not have municipal water available.

In accordance with the method of the present invention, outside the building costs are reduced significantly because the water supply capacity is designed to provide sufficient water for the limited number of heads which will be actuated by a high challenge fire, rather than, as in prior art systems, designed to provide sufficient water for about 100 or more sprinkler heads supplied from a single riser. Thus, even though the individual heads of the system of the present invention deliver larger quantities of water than individual prior art sprinkler heads, the total water requirement is much less. The difference will be great enough in many cases to enable municipal water to be used for supplying automatic extinguishant discharge systems for certain size and type buildings without the need for auxiliary equipment to increase the water capacity. Obviously, eliminating the need for a large water tank and the auxiliary equipment for delivering the water from these tanks to the buildings will provide considerable cost savings. For buildings located in rural areas where the municipal water supply may not be sufiicient, considerable savings can still be realized because a smaller water tank can be used along with less expensive auxiliary equipment for delivering the water from the tank.

The method of the present invention also results in considerable inside the building cost savings. In the preferred embodiment of the method, the large nozzle heads are spaced apart a greater distance than prior art systems to reduce the number of branch lines needed. Also, the riser feeding the branch lines is reduced to a 4 to 5 inch pipe size with threaded connections, rather than the flanged joints required for the large pipe sizes used for risers of prior art sprinkler systems. This not only provides savings in the cost of the pipe involved, but also savings in labor costs because less labor is required for installing threaded piping.

Limiting the number of heads which will be actuated by the fire can be accomplished in a number of ways. In accordance with a preferred embodiment a pressure floor is established so that a minimum pressure must exist at each head before it will open. The system is designed so that this minimum pressure will not be reached until a predetermined number of heads have been actuated.

In accordance with another embodiment, the number of heads which will be actuated is limited by wetting the thermal fuse element of each head after one of the heads has been actuated. This increases the temperature required to actuate subsequent heads. The heads closest to the fire will be elevated to a temperature sufficient to actuate the heads, but the heads furthest from the fire will not be actuated. Rather than wetting the thermal fuses, as just described, small heat shields can be moved into position after one of the heads has been actuated to shield the thermal fuses of the remaining heads in a manner to require higher temperatures to actuate the remaining heads.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, perspective view of a building having an automatic extinguishant discharge system employed in the method of the invention;

FIG. 2 is a plan view of the cross main and branch lines of the extinguishant discharge system of FIG. 1;

FIG. 3 is an enlarged, cross sectional view of one of the nozzle heads of the system shown in FIG. 1;

FIG. 4 is a fragmentary view taken on line 44 of FIG. 3;

FIG. 5 is a schematic view of a fire extinguishing system illustrating another embodiment of the method of the invention;

FIG. 6 is a fragmentary cross section taken on line 6-6 of FIG. 5;

FIG. 7 is a graph plotting water density ratios against corresponding wetted area ratios;

FIG. 8 is en enlarged, cross sectional view of one of the noule heads of the system illustrated in FIG. 5;

FIG. 9 is a plan view taken on line 99 of FIG. 8;

FIG. 10 is a lower end plan view taken on line 10- 10 of FIG. 8.

FIG. 11 is a schematic view of a fire extinguishing system illustrating still another embodiment of the method of the invention; and

FIG. 12 is an enlarged, cross sectional view of the nozzle heads shown in FIG. 1 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a building 10 shown in phantom lines is equipped with an automatic fixed fire protection system 12 embodying features of the invention. The system comprises a buried feed main 14 connected to a municipal water supply line 16 for delivering the extinguishant, in this case water, to a riser 18. The riser 18 is connected to a cross main 20 which, in turn, is connected to a plurality of branch lines 22. Each branch line has a plurality of nozzle heads 24 which are operated automatically in response to a fire, as will be described, to deliver a downwardly directed spray of water droplets on the fire. The buried feed main 14 extends beyond the riser 18 and can be connected to risers of other buildings or, in the case of a large building, to other risers in the same building. The cross main and branch lines are suspended near the ceiling of the building in a conventional manner. The system as thus far described is similar to a conventional automatic water sprinkler system employing sprinkler heads.

In accordance with the present invention, large nozzle heads are used in place of sprinkler heads, and the spacing of the nozzle heads is greater than the normal foot head spacing of prior art sprinkler systems. In the embodiment shown schematically in FIG. 1, the building height is about 30 feet, the nozzle heads on each branch line are spaced about feet apart, the spacing between branch lines is about 15 feet, and about 200 nozzle heads are supplied by the riser 18.

Referring to FIGS. 3 and 4 the construction of one of the nozzle heads 24 is shown in greater detail. Each nozzle head comprises a cylindrical body 26 having an internally threaded upward end 28. A pair of spiral vanes 30 and 32 are fixed within the body 26 for swirling water flowing downwardly therethrough when the nozzle is opened as will be described. The vanes 30 and 32 support a hollow central hub 34 which, in turn, slidably supports a rod 36 having a piston head 38 fixed on the lower end thereof. A pair of sealing rings 40 and 42 are positioned about the periphery of the head 38 and sealingly engage the wall of the outlet orifice 43 in the reduced lower end portion of the nozzle body 26.

The rod 36 is latched in the position shown in FIG. 3 by a rod 44 which extends slidably through an externally threaded boss 46 projecting from the side of the body 26. The left end of the rod 44 extends through the vane 32 and the wall of the central hub 34 into a slot 48 in the rod 36 to latch it in the position shown in FIG. 3.

A sleeve 50 is threaded on the end of the boss 46. The outer end of the sleeve is closed off by an externally threaded stub shaft 52 having a ring or yoke 54 thereon. The rod 44 slidably extends through the stub shaft 52 and the right end thereof engages a conventional thermal fuse element 56 positioned within the ring 54. The fuse element prevents movement of the rod 44 to the right, as will be described, until the heat of a fire fuses the element 56 so that it collapses. Since the thermal fuse element 56 is the standard type commonly used in conventional sprinkler heads now on the market, it will not be described in greater detail.

The rod 44 has a piston head 58 mounted thereon which slidably engages the internal wall of the sleeve 50. A spring 60 is positioned between the piston head 58 and the end of the stub shaft 52 to bias the piston head and rod 44 to the left with a predetermined biasing force. A passage 62 is formed in the boss 46 to communicate the space on the left side of the piston head 58 with the interior of the valve body 26. This allows the system water pressure which is about 40 psi. to bias the piston head 58 to the right against the opposing spring force to exert a positive pressure on the thermal fuse element 56. With this arrangement, the rod 44 will be driven to the right as soon as the fuse element 56 collapses in response to the heat of the fire to unlatch the rod 36. This enables the system pressure to act on the piston head 38 to expel it and the rod 36 from the nozzle and allow the water to spray out through the outlet orifice 43. If the system pressure in the nozzle 26 drops below a predetermined minimum pressure level, as will be described in greater detail hereinafter, the biasing force of the spring will maintain the piston head 58 and rod 44 in the position illustrated in FIG. 3 against the force developed by the reduced water pressure so that the rod 36 will not be unlatched when the thermal fuse element 56 collapses. Consequently, even if the heat of the fire is sufiicient to collapse the thermal fuse element 56, the nozzle 26 will remain closed until or unless the system water pressure in the nozzle exceeds the minimum predetermined pressure level to overcome the spring 60 and move the rod 44 to the right to unlatch the rod 36.

The lower end 64 of the valve body 24 extends downwardly to form a square end with four notches 66 at the comers thereof (three of which are visible in FIG. 3). The transformation of the circular outlet orifice 44 into a squared end portion, in combination with the swirling of the water produced by the vanes 30 and 32 produces a downwardly directed, solid cone, square spray pattern in a well known manner.

Referring again to FIGS. 1 and 2, good municipal water systems commonly provide 40 to 50 pounds of water at the main 16. With this in mind the riser 18, in accordance with the present invention, would employ 4 to 5 inch piping, the cross main 20 would employ 3 to 4 inch piping and the branch lines 22 would employ 2 to 3 inch piping. The outlet orifice 43 (FIG. 3) of each of the nozzle heads 24 would be about l inch to 1 it inches in diameter. With this arrangement the system of the present invention is designed to provide a minimum flow through the riser 18 of 550 gallons per minute and a maximum flow of 750 gallons per minute when 7 to 12 nozzle heads are opened.

In the specific embodiment shown in FIG. 1, the pressure supplied by the municipal water main 16 is 40 psi., the riser 18 is made of 4 inch piping, the cross main 20 is made of 3 i inch piping, the branch lines 22 are made of 2 inch piping, and the outlet orifice 44 of each of the nozzle heads 24 is l 35; inches in diameter. The spring 60 (FIG. 3) of each of the nozzle heads 24 is designed to hold the piston head 58 in the position shown in FIG. 3 after the thermal fuse element 56 collapses if the static water pressure in the unopened nozzle heads 24 drops below 10 psi. static pressure.

I-IIgh challenge fire tests conducted with the system 12 designed as just described, established that about seven heads will be actuated by a high challenge fire starting in a typical manner. Each head will provide about gallons per minute of water at about 10 psi. dynamic (flowing) pressure and will cover a floor area of about 225 square feet. The individual branch lines carry about 300 gallons per minute when three heads are operating on each branch line. The remaining heads on the same branch line will not be operating because the static pressure level at each of these heads will be below the aforementioned minimum static pressure floor.

With the head arrangement shown in FIGS. 1 and 2, the aforementioned seven heads will cover a total area of about 1,575 square feet. With the system of the present invention, it is assumed that the fire will not get beyond the 1,575 square foot area before the seven heads are on, and that no fire will be able to get beyond the 1,575 square foot area after these heads are on. This is based on testing experience which shows that a typical high challenge fire occupies less than 100 square feet of floor area when the first head opens.

The system 12 functions automatically to provide useful water flow to the heads over and around the fire with a minimum water density of 015 gallons per minute per square foot of floor area. At the same time, the system denies water to unopened heads if the static pressure at these heads is below the minimum pressure floor, because the opening of these heads would jeopardize the fire fighting capability of the heads which have already been opened. This also avoids wetting remote floor areas to cause unnecessary water damage as in prior art systems. Thus, no matter how many thermal fuse elements 56 collapse due to the heat of the fire, the system 12 will provide sufficient water to supply the nozzles in the best position to actually fight the fire and provide useful exposure protection by wetting areas immediately surrounding the fire. This is accomplished with a 4 k inch riser 18 having a maximum water flow rate of about 700 gallons per minute.

Referring to FIG. 5, a fire extinguishing system 100 is shown which illustrates another embodiment of the invention. The system is depicted as installed in a building space generally designated by the reference numeral 110 and defined by a floor 112 a ceiling 1 14 and side walls 1 16. The stacks of piles bearing reference letters A-G represent combustible material or fuel piles stored within the space 110 as in a conventional warehouse, storage facility or the like.

Supported in depending fashion from the ceiling 114 are a plurality of spaced nozzle heads 118 each having a thermally responsive fusable element 120 and a discharge orifice 122, as will be described in greater detail hereinafter. When the ambient temperature in the vicinity of a fusable element 120 of a head 118 reaches a predetermined point, the discharge orifice 122 on that head is opened to disperse a solid cone spray S of extinguishant. The extinguishant is delivered to the respective nozzles by a riser, cross main and branch lines similar to those illustrated in FIG. 1. In the schematic showing of FIG. 5, the riser 124 is shown and one of the branch lines 126 which it supplies.

In this embodiment, the fire extinguishing system 100 incorporates the additive injection system disclosed in copending applicationSer. No. 864,757, filed on Oct. 8, I969 and entitled Additive Injection System. An additive slurry of a water swellable polymer or gelling agent is injected automatically into a line 130 which supplies the riser 124 with water from a water supply main 132 through auxiliaries such as cutoff valves and the like. This forms an ablative gel] in the riser 124 as fully disclosed in the aforementioned copending application, and reference is made to this application for a detailed description of this injection apparatus.

In general, however, and as depicted by the legend bearing blocks in FIG. 5, the injection apparatus operates to sense the flow of water called for by the opening of a nozzle 118 and to energize a power source, such as a motor, to pump or inject the additive through a mixer to the line 130. As fully described in the aforementioned copending application, the injection system operates on a no-inject failure mode to insure that at least an adequate supply of plain water will pass from the water supply main 132 through the line 130, riser 124 and branch lines 126 to the heads 1 18.

Referring to FIGS. 8-10, the construction of one of the nozzles 118 is shown in greater detail. The nozzle comprises a body 141 having an inlet portion 142, an intermediate portion 143, and a discharge portion 144. The inlet portion 142 is internally threaded as at 146 to facilitate attachment to an externally threaded fitting connected to and depending from the branch line 126. The inlet portion 142 defines an inlet area which is relatively large compared to the area defined by the discharge portion 144. This minimizes pressure losses at the inlet and provides a potentially large supply of extinguishant to the discharge portion when the nozzle head is actuated.

A threaded nipple member defining an opening 171'is engaged with an internally threaded opening 172 in a boss 1 73 positioned at the transition between the inlet end portion 142 and the intermediate portion 143 of the nozzle. The opening 171 is sized to permit axial movement of a rod 160 relative thereto.

A coupling member 175 having an interior cavity 176, a first internally threaded opening 177 and a second internally threaded opening 178 is threadably mounted on the nipple 170. A first annular member 180, such as a washer, is provided about an intermediate portion of the rod 160 and rests against a surface 182 defined by the end of the nipple 170. A spring 184, also located about an intermediate portion of the rod 160, is contained within the cavity 176 and includes a first end 185 abutting the first annular member 180 and a second end 186 abutting a second annular member 187, such as a washer, located about the rod 160. A third annular member 189 provides a shoulder for retaining the rod 160 in the latched position shown in FIG. 8 with the spring 184 in a compressed state. The annular member 189 may constitute an integral part of the rod 160, or may be eliminated if the head portion 190 of the rod 160 has a diameter which is sufficiently great to provide a shoulder against which the annular member 187 may rest.

A conventional fire detector, designated generally at 192, comprises a housing 193 secured to a base 194 having a threaded portion 195 in threaded engagement with the mating threads in the opening 178 of the coupling member 175. The base 194 and the portion of the housing 193 adjacent thereto together define an opening 197 for slidably receiving the head portion 190 of the rod 160.

It is an advantage of the system to use conventional fire detectors for either water discharge systems or ablative gell discharges systems because such detectors are presently approved by fire protection agencies, insurance companies, trade associations and other interested authorities. In this manner, the accumulated experience and the low cost of the conventional fire detectors may be used to great benefit. However, this system is not confined to actuation by either the illustrated thermally actuated device 192 or by known fire detection elements.

A fire responsive element, designated generally as 199, comprises a first fusable link portion 200 and a second fusable link portion 201 mounted in the housing 193 between a first supporting member 202 and the end of the head portion 190. The element 199 is designed to forsake its structural rigidity at a predetermined temperature, thus permitting the head portion 190 of the rod 160 to extend axially under the influence of the spring 184 thereby freeing the rod 160 from its restraining influence on a rod 150. In the absence of a fire or thermal actuation, the transverse shear strength of the fusable link portions 200 and 201 is sufficiently great to withstand the force of the spring 184 acting on the rod 160 and thus retain the rod 160 in the position illustrated in FIG. 8.

A fusable nut 205, responsive to a predetermined temperature, is located adjacent to a plug 151 in a discharge opening 122 of the nozzle head. The fusable nut 205 provides a safeguard against the expulsion of rod 150 in the event that the fusable link 199 is inadvertently actuated. It also prevents an accumulation of dirt and grime in the discharge opening 122 which may otherwise affect the expulsion of the rod 150 from the nozzle head in the event of fire.

If both the fusable element 199 and the fusable nut 205 have been thermally actuated, the nozzle head is opened to permit the extinguishant to be discharged from the discharge opening 122 in a predetermined spray pattern. A fusing of the link portions 200 and 201 permits the rod 160 to be displaced axially by the force of the spring 184 exerted through the member 187 against the shoulder of the annular member 189. The limited axial movement of the rod 160 is sufficient to free the protuding end portion 161 from its engagement with an opening 162 in the expellable rod 150. The pressure of the extinguishant against the plug 151 causes the plug and rod 150 to be expelled from the discharge opening 122.

A pressurized bellows assembly, designated generally at 206 is provided which comprises a fixed member 207 secured to a pair of accordion bellows members 208 and 209 which, in turn, are secured to an axially displaceable movable member 210. The accordion members 208 and 209 define a closed annular cavity 215 which contains a predetermined quantity of compressable material, for example, an inert gas. When the pressure of the extinguishant at the inlet to the nozzle head is at its maximum for the system, for example, when no other nozzle heads have been actuated, the volume of the closed cavity 215 is at a minimum since the pressure within the cavity seeks to balance the inlet pressure of the extinguishant. Under this condition, the distance between the fixed member 207 and the movable member 210 is at a minimum, permitting a maximum flow of extinguishant to the nozzle orifice 212 through the passage designated generally at 213.

When the inlet pressure of the extinguishant decreases, for example, from increased demands on the system by the actuation of other nozzle heads, the flow modulating assembly 206 operates to achieve a hydrostatic balance. Since the quantity of compressable fluid in cavity 215 is fixed, the volume of the cavity increases until the pressure exerted from within the cavity is equal to the pressure of the extinguishant on the exterior of the cavity. Because the cavity 215 is incapable of circumferential expansion, the distance between the fixed member 207 and the movable member 210 increases to a maximum, thus constricting the effective discharge passage 213 leading to the nozzle orifice 212. When the passage to the nozzle orifice is thus constricted, the flow rate of extinguishant is reduced, so that the spray pattern of the extinguishant from the nozzle head is maintained. Also, the inlet pressure to the nozzle head is increased to maintain a higher inlet pressure to the overall system.

Referring to FIG. 10, a plurality of radially extending, generally V-shapcd notches 219 are in communication with the discharge opening 122 and with the exterior of the nozzle head. The extent of the spray pattern produced by the nozzle head is determined by the maximum width of the notches, the depth of the notches, the flow rate of the extinguishant and the like. These notches, in combination with the swirling produced by swirling vanes 147, produce a rectangular, downwardly diverging pyramid shape spray pattern indicated by the phantom lines 2 in FIG. 6. Although this particular rectangular or square configuration of the spray is not essential, it is desirable that the area developed at the intersection of the spray with the horizontal plane define a polygon capable of complementing adjacent similarly configured areas.

In the event the inlet pressure falls below a predetermined level, the movable member 210 closes off the nozzle orifice 212 to prevent flow of extinguishant even though the thermal fuse element has been collapsed to unlatch the rod 150. As described in connection with the first embodiment, this pressure can be set slightly below l0 pounds static pressure. As will be described in greater detail hereinafter, this keeps the total demand for extinguishant from the supply system within the capabilities of the system.

To facilitate clearer understanding of the fire extinguishing system of FIGS. 5 and 6 reference is made to the graph in FIG. 7. In the graph, the ratio of actual delivered density of the extinguishant to the design or optimum density is assigned numerical values on the ordinate, whereas the ratio of actual area of coverage to design or optimum area of coverage for a nozzle head operating under given conditions of orifice size and line pressure is indicated numerically on the abscissa. A curve on the graph is plotted for a single nozzle head delivering extinguishant at uniform flow rates. Thus, at the point 0 on the curve X, where actual to design density and actual to design area of coverage are at unity, optimum efficiencies are achieved in terms of nozzle operation corresponding to design parameters. If however the actual area increases relative to the area for which the nozzle is designed, the ratio of actual to design densities falls off quickly as indicated by that portion of the curve to the lower right of the point 0. On the other hand, where the ratio of actual area covered to design area of coverage is less than 1, the actual density relative to design density increases quite shrply as indicated by the curve above the point 0. In

terms of the curve illustrated in FIG. 7 therefore, the

system 100 departs from traditional fixed fire extinguishing systems of the type heretofore available by operating each nozzle in the portion of the curve to the upper left of the point 0, or in a manner such that any error or departure from design parameters is towards the side of increasing the density of extinguishant reaching the fuel surfaces even though some area of coverage may be sacrificed.

The manner in which the principles expressed by the curve in FIG. 7 are carried out in practice according to the present invention may be seen by reference to FIGS. and 6 of the drawings. As previously indicated, each of the nozzles 118 delivers a downwardly diverging pyramid shaped spray S, the angle of divergence being designated in FIG. 5 by the reference letter a. As the spray intersects a horizontal reference plane depicted by the dashed line P in FIG. 5, it establishes in the reference plane an area of coverage Z or an area of head responsibility as shown in FIG. 6 of the drawings. It is important that the reference plane P be selected so that it lies at or near the upper most surface of fuel within the space 110 to be protected, and that the perimeters of the areas of responsibility Z for each nozzle be spaced for the perimeters of corresponding areas for adjacent nozzles as may be seen in FIGS. 5 and 6 of the drawings. Such spacing or underlap between the area Z may vary depending on the spray angle a of the nozzles 1 18. For example, if the spray angle is less than 90 the spacing between the areas or the underlap may be in the order of l V; feet whereas if the spray angle is more than 90 the underlap may be increased to the order of 2 i feet. While the precise maximum spray angle a may vary somewhat depending upon the height of the space to be protected, the maximum spray angle to be used for most efficient operation of the system 100 is 140 for each nozzle head.

In the operation of the system, assuming a fire develops in the fuel pile B, the temperature above the burning fuel will increase quickly to release the fuse 120 on the nozzle head directly above the pile B. Because the density of the spray S from the actuated nozzle head is designed for the highest fuel pile in the space 110, extinguishant at densities at least as great as the designed density will be delivered directly down on the pile to extinguish the fire. Should a tire develop in a lower pile such as, for example, the pile A as shown in FIG. 5 of the drawings, the extinguishant is reaching the pile A from the same head will be at a substantially lower density due to the spread of the extinguishant as it falls downwardly. Because the lower height of the pile A constitutes a significantly lower fire hazard as compared with the pile B, the fall off in density will be of little consequence in terms of extinguishing the fire.

Referring to FIG. 11 of the drawings, a fixed fire extinguishing system 300 is shown which illustrates still another embodiment of the invention. The system 300 includes a plurality of nozzle heads 310a 310f positioned in spaced relation below a ceiling 312 of an enclosed space 314 being protected by the system. In conventional fashion, nozzles 310 are supplied by a fluid extinguishant such as water from a municipal water main (not shown) through a riser, cross main and branch lines as previously described. In the schematic showing of FIG. 1 l, a riser 316 is shown along with one of the branch lines 318. The system is maintained with an extinguishant under pressure designated by the arrow P. Each of the nozzles 310 is maintained in a clmed position under the control of a fire responsive element 322 as will be described in more detail hereinafter.

For purposes of illustration, the space 314 shown in FIG. 11 contains combustible material or fuel piles designated by the reference letters F. As in the previous embodiments, when a fire exists within the space, the heat rising therefrom will be sensed by the fire responsive element 322 associated with the head or heads 310 immediately above the fire to bring about actuation of the system. Hence, the development of a fire in the fuel piles beneath the head 310b, for example, will actuate that head to disperse extinguishant directly down on the fire. Depending upon the magnitude of the fire and particularly the magnitude of the heat generated thereby, a certain amount of time will elapse between the start of the fire and the actuation of the head 310b and then the heads 310a and 310c to bring about its extinguishment.

With smaller fires, it is possible that the activation of only a few heads will deliver a sufficient amount of extinguishant to extinguish the fire. With larger fires, however, where an extreme amount of heat is developed, the circulation of the heat by convection within the space 314 as depicted by the arrows H in FIG. 11 will actuate heads positioned remotely from the actual fire, such as for example, the heads 10e and 10f. Quite obviously, the actuation of such remote heads will have little or no effect upon the extinguishment of the original fire and moreover will reduce the pressure available for those heads already dispersing extinguishant to the fire in such a manner that the overall system is rendered ineffective to extinguish the fire. The nozzle heads 310 are specifically designed to inhibit the activation of remotely located heads and thus overcome this problem.

Referring to FIG. 12, the construction of one of the nozzle heads 310 is shown in detail. It can be observedthat it is basically the same nozzle shown in FIG. 8 with a pressure actuated heat shield added thereto. Briefly, the nozzle comprises a body 324 having an inlet 326 adapted to be connected directly to a conduit 320 (FIG. 11) extending downwardly from the branch line 318. An outlet orifice 328 at the lower end of the body is normally closed by an expellable plug 330 mounted on the lower end of a rod 332. A transversely slidable rod 334 latches the rod 332 against displacement from a discharge orifice 328 under the influence of line pressure. Swirling vanes 336 and a pressure responsive bellows 338 are provided as previously described in connection with the nozzle 118 of FIG. 8. The rod 334 is held against the bias of a compression spring 340 acting on a collar 342 secured on the rod by a collapsable linkage assembly including arms 344 secured against collapse by a fusable link 346, the latter assembly itself being well known in the fire sprinkler art.

When temperature in the vicinity of the fusable link 346 reaches a predetermined point, the linkage including the arms 344 collapse out of the way, permitting the spring 340 to move the rod 334 out of engagement with the rod 332 to open the discharge orifice of the head 328, assuming of course that the pressure at the inlet orifice 326 is high enough to prevent the bellows 338 from closing the outlet orifice 328 as previously described in connection with the nozzle head 118 of FIG. 8.

The temperature at which the fusible link 346 is released is made dependent on line pressure by means of a heat shield 348 which can be moved between the dotted and full line positions as shown. The heat shield 348 is supported on one arm of a bell crank 350 pivoted from a lug 352 extending from a bushing 354 enclosing the rod 334 and connected to the body 324. The other arm 356 of the bell crank is formed with a slot 358 which receives a connecting pin 360 on the end of a plunger 362. The opposite end of the plunger 362 extends within a chamber 364 defined by a cap 365 threaded in a boss 366 on the body 324 and is connected to a flexible diaphragm 368. A port 370 in the boss 366 places the chamber 364 in fluid communication with the interior of the body 324 and thus with line pressure existing at the inlet 326 to the nozzle 310.

A compression spring 372 acting between the cap 365 and a collar 374 on the plunger 362 biases the plunger and the bell crank 350 and the heat shield 348 to the solid line position shown in FIG. 12. Line pressure, in the chamber 364 acting against the diaphragm 368 tends to urge the plunger in a direction opposing the bias of the spring 372, or to the phantom line position indicated in FIG. 12. Thus, when line pressure existing within the body 324 is sufficient to overcome the biasing effect of the spring 372, the heat shield will be held in the position illustrated in phantom lines in FIG. 12 away from the fusable link 346. When line pressure drops below about psi. static pressure, the force exerted by the spring is larger than that developed by fluid pressure acting against the diaphragm 368 and the heat shield 348 moves to the solid line position to encircle and shield the fusible link 346.

Initially, the line pressure P (FIG. 1 1) throughout the system is at the pressure provided by the municipal water main which, as in the embodiment of FIG. 1, is about 40 psi. This maintains the heat shields 348 associated with the nozzle heads 310 in the phantom line position so that they do not shield the fusible links 346. In this condition, should a fire develop, each of the nozzle heads in the system is equally responsive to the temperatures resulting from the fire. Upon the development of the fire, the head or heads nearest the fire will be actuated to disperse the extinguishant downwardly on to the burning fuel surface. If however, the line pressure at the unopened heads drops below a static pressure of 10 psi., as it may after a certain number of heads are opened, such as about seven as in the system of FIG. 1, the heat shields are moved automatically to the solid line position to shield the fusible links 346 of the unopened heads so as to delay or inhibit actuation of these heads positioned remotely from the fire.

The heat shield 348 as shown in FIG. 12 is in the form of a metal trough-like structure capable of deterring the effect of increased ambient temperatures on the fusible links 346. As an alternative to the heat shield, the fusible links 346 may be cooled directly by the drip tube technique disclosed in FIGS. 3-6 of may aforementioned copending application Ser. No. 885,501 In accordance with this technique, water from the system is dripped my on the fusible links 346 when the static pressure at unopened heads drops below the aforementioned minimum value to cool the fusible links which then require a higher temperature to fuse them.

From the foregoing, it will be apparent that each of the systems 12, and 300 described above effectively limits or controls the number of heads which will be actuated by a high challenge fire. This is accomplished by control means associated with each head, in addition to the conventional temperature responsive means, for determining whether the heads will be opened to spray extinguishant on the fire. This also can be accomplished by control means located apart from the nozzle heads. For example, a flowmeter could be mounted on the riser 18 of FIG. 1 to provide an electrical signal when the flow through the riser reaches the aforementioned 700 gallons per minute when about seven noule heads are opened by a fire. The electrical signal could then be transmitted to suitable solenoid actuated latch mechanisms associated with each of the nozzle heads to prevent the unopened heads from opening even if their thermal fuse elements subsequently are fused by the fire.

Because the number of heads which will open is limited, the 40 psi. water pressure supplied by the municipal water main 16 of FIG. 1, for example, is adequate for supplying the branch lines connected to the riser 18 without having to resort to a gravity or suction feed tank to provide additional capacity. This results in significant outside the building cost savings as mentioned at the outset of this application. The resultant smaller piping with threaded connections and the reduction in the number of branch lines reduces the material and labor costs to provide the aforementioned inside the building cost savings.

' Further, the effectiveness of the systems 12, 100 and 300 is superior to prior art sprinkler systems because these systems put larger quantities of extinguishant on and immediately around the fire in large drop sizes which can penetrate fire plumes of high challenge fires. Also, the unnecessary water damage caused by the actuation of remotely located heads is eliminated.

As will be seen from the system 100 shown in FIGS. 5-10, the method of the present invention is well suited for use with ablative fluid systems. The ablative fluids are thicker than plain water but can be handled effectively by the large direct spray nozzles disclosed herein which pass larger quantities of fluid at lower flow rates. With this type nozzle the ablative fluids produce larger, heavier droplets having superior fire plume penetrating capability as compared to plain water. However, should the injection apparatus fail to inject the slurry additive to the water, the system 100 fails safe by spraying water on the fire in a more effective manner than prior art sprinkler systems.

I claim:

1. A method of fire protection comprising the steps of disposing a plurality of extinguishant dispersing heads in a space to be protected, delivering extinguishant from a source of supply to all of the heads in said space, actuating the heads in a sequence dictated by information received from a fire developing in said space, and controlling the opening of said heads in a manner to reduce the total number of heads in said space which will be opened to deliver extinguishant to the fire as compared to the total number of heads in said space which would be opened by the same information received from the fire acting on the same system without said control means.

2. The method as defined in claim 1 wherein each head is individually controlled in said step of controlling.

3. The method as defined in claim 1 wherein said step of controlling comprises the step of preventing additional heads from being actuated when the system reaches a predetermined condition after a limited number of heads have been opened.

4. The method as defined in claim 1 wherein said step of controlling is effected in response to a predetermined condition of said extinguishant.

5. The method as defined in claim 4 wherein said step of controlling comprises the step of maintaining unopened heads closed when the pressure of the extinguishant in said system drops below a predetermined level.

6. The method as defined in claim 4 wherein said step of controlling is effected in response to the static pressure of the extinguishant at each unopened head.

7. The method as defined in claim 1 wherein said step of controlling comprises the step of regulating the point at which said fire responsive means actuates said heads.

8. The method as defined in claim 1 wherein said step of delivering comprises the step of delivering extinguishant at a maximum delivery rate capacity sufficient to supply the reduced number of heads which will be opened by the same information received from the same fire and insufficient to supply the number of heads which would be opened by the same information received from the same fire acting on the same system without said control means.

9. The method as defined in claim 1 wherein the extinguishant is discharged from each opened head directly down on the fire in a solid cone spray pattern having a spray angle less 180.

10. The method as defined in claim 1 wherein said step of delivering comprises the step of supplying water to said heads and introducing an ablative additive to the water to convert the water to an ablative fluid to be dispersed from said heads.

11. The method as defined in claim 1 wherein said step of actuating is done at all times and wherein said step of controlling comprises the step of preventing the individual heads from opening after they have been actuated.

12. The method as defined in claim 1 wherein said steps of actuating and controlling together enable a predetermined number of heads to be opened when actuated by the fire responsive means and thereafter restrict the opening of additional heads.

13. A discharge head for a fire extinguishing system comprising a body member having an inlet for connection to a source of extinguishant and an outlet for discharging extinguishant, means adapted to cooperate with said body member and move from a normal position in which extinguishant discharge from said outlet is prevented to a second position in which extinguishant discharge from said outlet is permitted, and means responsive to a predetermined fire condition and to an extinguishant pressure greater than a predetermined pressure for permitting movement of said first mentioned meansto said second position, said responsive means being independent of changes in said pressure after said first mentioned means has moved to said second position.

14. The head of claim 13 wherein said first mentioned means comprises plug means for said outlet and latching means for normally latching said plug means in said outlet.

15. The head of claim 14 wherein said responsive means cooperates with said latching means for causing said latching means to release said plug means.

16. The head of claim 13 wherein said first mentioned means comprises plug means for said outlet and retaining means for normally retaining said plug means in said outlet.

17. The head of claim 16 wherein said responsive means cooperates with said retaining means for causing said retaining means to release said plug means.

18. The head of claim 16 wherein said retaining means comprises a latching assembly for normally latching said plug means in said outlet and connecting means for normally connecting said plug means relative to said body member.

19. The head of claim 18 wherein said responsive means comprises first control means cooperating with said latching assembly for releasing said plug means in response to said predetermined fire condition, and second control means cooperating with said connecting means for releasing said plug. means in response to said extinguishant pressure.

r Column 13 line UNITED STATES PA'LENT 0mm; CERTIFECATE F CRRECTION PO-lOUU Dat Maroh 27 W72 Eatent No.

Inventor(s L. certified that error appears in the above-identified patent It is t are hereby corrected as shown below:

and that said Letters Paten "which should read =--which in turn--. protudinq ehould read -.-protruding-. 5, shrply should read sharply". 24, spaced for should read -spaced from-. 48, "extinquishant is" should read in--. 62, "of may" should read --of my-. 65, "dripped my" should read dripped Colman Column 9, ine

Column 16, line Column ll, line Column line ll, --extinguishant Column 13, line -directly-.

Signed and sealed thie 5th day of November 1974.

(SEAL) Attesc Cu SHALL DANN Cissione r of Patents MeCOY M, GIBSCN JR. Attesti ng Officer 

1. A method of fire protection comprising the steps of disposing a plurality of extinguishant dispersing heads in a space to be protected, delivering extinguishant from a source of supply to all of the heads in said space, actuating the heads in a sequence dictated by information received from a fire developing in said space, and controlling the opening of said heads in a manner to reduce the total number of heads in said space which will be opened to deliver extinguishant to the fire as compared to the total number of heads in said space which would be opened by the same information received from the fire acting on the same system without said control means.
 2. The method as defined in claim 1 wherein each head is individually controlled in said step of controlling.
 3. The method as defined in claim 1 wherein said step of controlling comprises the step of preventing additional heads from being actuated when the system reaches a predetermined condition after a limited number of heads have been opened.
 4. The method as defined in claim 1 wherein said step of controlling is effected in response to a predetermined condition of said extinguishant.
 5. The method as defined in claim 4 wherein said step of controlling comprises the step of maintaining unopened heads closed when the pressure of the extinguishant in said system drops below a predetermined level.
 6. The method as defined in claim 4 wherein said step of controlling is effected in response to the static pressure of the extinguishant at each unopened head.
 7. The method as defined in claim 1 wherein said step of controlling comprises the step of regulating the point at which said fire responsive means actuates said heads.
 8. The method as defined in claim 1 wherein said step of delivering comprises the step of delivering extinguishant at a maximum delivery rate capacity sufficient to supply the reduced number of heads which will be opened by the same information received from the same fire and insufficient to supply the number of heads which would be opened by the same information received from the same fire acting on the same system without said control means.
 9. The method as defined in claim 1 wherein the extinguishant is discharged from each opened head directly down on the fire in a solid cone spray pattern having a spray angle less 180*.
 10. The method as defined in claim 1 wherein said step of delivering comprises the step of supplying water to said heads and introducing an ablative additive to the water to convert the water to an ablative fluid to be dispersed from said heads.
 11. The method as defined in claim 1 wherein said step of actuating is done at all times and wherein said step of controlling comprises the step of preventing the individual heads from opening after they have been actuated.
 12. The method as defined in claim 1 wherein said steps of actuating and controlling together enable a predetermined number of heads to be opened when actuated by the fire responsive means and thereafter restrict the opening of additional heads.
 13. A discharge head for a fire extinguishing system comprising a body member having an inlet for connection to a source of extinguishant and an outlet for discharging extinguishant, means adapted to cooperate with said body member and move from a normal position in which extinguishant discharge from said outlet is prevented to a second position in which extinguishant discharge from said outlet is permitted, and means responsive to a predetermined fire condiTion and to an extinguishant pressure greater than a predetermined pressure for permitting movement of said first mentioned means to said second position, said responsive means being independent of changes in said pressure after said first mentioned means has moved to said second position.
 14. The head of claim 13 wherein said first mentioned means comprises plug means for said outlet and latching means for normally latching said plug means in said outlet.
 15. The head of claim 14 wherein said responsive means cooperates with said latching means for causing said latching means to release said plug means.
 16. The head of claim 13 wherein said first mentioned means comprises plug means for said outlet and retaining means for normally retaining said plug means in said outlet.
 17. The head of claim 16 wherein said responsive means cooperates with said retaining means for causing said retaining means to release said plug means.
 18. The head of claim 16 wherein said retaining means comprises a latching assembly for normally latching said plug means in said outlet and connecting means for normally connecting said plug means relative to said body member.
 19. The head of claim 18 wherein said responsive means comprises first control means cooperating with said latching assembly for releasing said plug means in response to said predetermined fire condition, and second control means cooperating with said connecting means for releasing said plug means in response to said extinguishant pressure. 